Vehicle operators may sometimes experience physical impairment or distress while operating a vehicle, which may endanger other people or the operators themselves. Monitoring the vital signs of vehicle operator may provide useful information for determining the ability of the vehicle operator to continue operating the vehicle. Four primary vital signs reflect essential body functions, namely, respiration rate, pulse rate, blood pressure, and body temperature. Respiration rate may include the number of breaths a person takes per minute. An abnormal respiration rate may indicate a potentially serious clinical event. Continuous monitoring of the respiration of a vehicle operator may help to prevent high-risk situations. However, conventional respiration sensors may be intrusive in nature and/or may be inconvenient for a vehicle operator to use on a regular basis.